Telcordia NEBS Requirements
NEBS GR-63-CORE ISSUE 5R4-18 [138] All fan-cooled equipment occupying greater the 1U of vertical rack space (45mm [1.75in]) shall be equipped with filters. Fan filters shall be replaceable with equipment operating. Rectifiers, distribution bays, and sealed equipment with only outside fan cooling do not require filters.
O4-19 [206] It is an objective that fan-cooled equipment occupying 1U of vertical rack space (45mm [1.75in]) or less should be equipped with filters. These air filters should be replaceable with equipment operating. Rectifiers, distribution bays, and sealed equipment with only outside fan cooling do not require filters.
R4-20 [139] All equipment fan filters used in equipment occupying over 2U of vertical rack space (90 mm [3.5 in]) shall have either a:Minimum dust arrestance of 80%, per ASHRAE Standard 52.1-1992 Minimum Efficiency Rating Value (MERV) of 4, per ASHRAE Standard 52.2-2017
R4-21[176] All equipment fan filters used in equipment occupying 2U of vertical rack space (90mm [3.5in]) or less shall have either a:Minimum dust arrestance of 65%, per ASHRAE Standard 52.1-1992 Minimum Efficiency Rating Value (MERV) of 2, per ANSI/ASHRAE Standard 52.2-2017
R4-22 [140] Construction and system fit of equipment fan filters shall prevent any air bypass. Inadvertent leakage that may result from mechanical fits or tolerances, (examples may include spaces between circuit pack face plates, connector or cable matrices, chassis screw or mounting holes, etc.), is not considered bypass.
NOTE: Polymer filter media must also meet the fire-resistance requirements per Section 4.2.3.1, “Materials, Components, Wire, and Cable Fire-Resistance Criteria.”
R4-23[141] Construction and system fit of equipment fan filters shall prevent any air bypass. Inadvertent leakage that may result from mechanical fits or tolerances, (examples may include spaces between circuit pack face plates, connector or cable matrices, chassis screw or mounting holes, etc.), is not considered bypass.
R4-24 [142] Equipment shall have a provision for fan-filter replacement without particulate contaminants from the filter being introduced into equipment. If filters can be changed with fans operating, filter replacement methods that minimize touching the media and/or dislodging captured particulates shall be specified. Filter designs with rigid frames that are withdrawn from the airflow for removal satisfy the intent of this requirement.
R4-25 [143] The equipment manufacturer shall provide a method for determining equipment fan filter replacement schedules. This guideline shall be included in the product documentation.
O4-26 [144] If possible, active alarming should be provided to indicate the need for fan filter replacement.
R4-27 [145] Equipment fan filters shall be single use and not the types that require cleaning.
O4-28 [194] It is an objective that equipment fan filters utilize recyclable materials.